Prefabricated building panel wall



B. C.'BERNEY E L IPREFABRICATED BUILDING PANEL'WALL .Aug.- 22, 1967 v I Filed Jan. 22, 1965 I 3 Sheets-Shani I NVENTORS BEHNEY.

.BZ'HNARD 5.

BY HENRYA. 503551;.

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ATTYQ B. c. B E RNEY ET AL PHEFABRICATED BUILDING PANEL Ailg zz, 1967 Filed Jan. 22,1965 7 WALL 3 Sheets$heet 3 United States Patent 3,336,709 PREFABRICATED BUILDING PANEL WALL Bernard C. Berney and Henry A. Goebel, Indianapolis, Ind., assignors to Mosaic Building Products, Inc., Mooresville, Ind., a corporation of Indiana Filed Jan. 22, 1965, Ser. No. 427,307 v4 Claims. (Cl. 52-309) This invention relates to prefabricated building panel walls and more particularly to a prefabricated building panel which readily can be constructed in various sizes for utilization in the construction of outer walls of modern buildings.

The building panel embodying the invention will be illustrated in its utilization as an outer wall of a multiple story, reinforced concrete building wherein the load hearing strength is provided by the steel skeleton and the reinforced concrete floors.

Because modern high rise building structures are designed so that the strength of the building is provided by its skeleton and/ or its reinforced concrete floors, the outer walls of the building usually are required to have sufiicient strength only to enclose the inhabited spaces, to protect those spaces against changes in the weather, and to provide means for both exterior and interior decorative treatments. A prefabricat d building panel embodying the invention in addition pron'des both acoustical and thermal insulations in order to minimize the transmision of noise from outside of the building and to control the spread of fires which might start in one of the occupied spaces on a floor.

It is, therefore, the principal object of the instant invention to provide a prefabricated building panel having means for the mounting and retention thereon of exterior facing materials of various types suitable for use as the outer wall of a building and which has suflicient structural strength to support itself, to provide for the support of windows, and to resist wind forces to which the exterior of such a building is exposed.

It is yet another object of the instant invention to provide a prefabricated building panel which can be constructed in modular units of various dimensions, say, four feet by eight feet, five feet by ten feet, eight feet by eight feet, ten feet by ten feet, etc., and which possesses the ability to withstand severe fire tests, achieving what is frequently called a two-hour ratingthis degree of resistance to breakdown under severe conditions being greater than the cumulative resistance of its component parts,

Other and more specific objects and advantages of a prefabricated building panel embodying the invention will be better understood from the following specification and from the drawings in which: FIG. 1 is a fragmentary view in perspective of a portion of the outer elements of a high rise building, and illustrating the utilization of prefabricated building panels as the outer Walls of such a building providing for exterior decorative treatment and the mounting and support of suitable windows and/ or other openings;

FIG. 2 is a greatly enlarged, fragmentary detailed view showing typical panel mounting means;

FIG. 3 is a detailed view in perspective of a part of the panel mounting means;

FIG. 4 is a front view in elevation of a panel according to the invention with successive layers of materials broken away to show the construction thereof; 1

FIG. 5 is a greatly enlarged horizontal sectional view taken along the line 55 of FIG. 4;

FIG. 6 is a front view in elevation of the cold side of a test panel constructed according to the instant invention as arranged for fire resistant testing and showing the position of certain temperature measuring thermocouples on the unexposed face of the panel;

ing elements usually is FIG. 7 is a fragmentary, vertical sectional view taken along the line 77 of FIG. 6; and

FIG. 8 is a time-temperature chart of the fire test of the panel shown in FIG. 6.

A typical building, a small part of which is illustrated in FIG. 1, has a plurality of superposed floors 21, 22, etc., each of which consists of reinforced concrete suitably supported and cantilevered by structural steel framework (not shown). The vertical distance between the floors 21 and 22 may be any suitable dimension as selected by the building architect say, for examples, ten feet, eleven feet, twelve feet, etc. In the particular building illustrated, the reinforced concrete floors 21 and 22 extend horizontally only to the outer wall generally indicated by the reference number 23 and which is shown as being made from assembled modular panels, although, of course, panels embodying the invention may also be used in buildings such as apartment houses where there may be balconies and the like on the outer sides of the wall 23.

The wall 23 is formed by assembling prefabricated building panels such as panels 24 in which are set windows 25, solid panels 26, and other panels (not shown) which may consist essentially of spandrels and door ways, for example. It will be appreciated, of course, that the particular panels 24 and 25 are only illustrative of prefabricated building panels embodying the invention and that their utilization as illustrated in FIG. 1 to form the outer wall of a high rise reinforced concrete building is also merely illustrative of the various types of construction for which they are suitable. In describing panels embodying the invention reference will be made to solid panels 26 but the solid portions of Window containing panels 24 are similarly constructed.

According to the instant invention, the prefabricated building panel 26 comprises a perimeter frame including vertical channels 27 which are welded at the upper and lower corners of the panel to horizontally extending channels 28 similar to the vertical channels 27. Each of the chanels 27 or 28, whether vertical or horizontal, comprises a crossweb 29 and spaced, parallel arms 30. The crosswebs 29 may be perforated with a plurality of openings 31 to reduce their weight and are so shown. The channels 27 and 28 are assembled with their arms 30 turned outwardly.

When an individual prefabricated building panel 26 has a horizontal dimension in excess of two feet, for example, it is desirable to run additional vertical studding channels 32 therethrough which also are welded or otherwise secured to the horizontal channels 28.

When prefabricated building panels 24 or 26 are placed in edge to edge adjacency the rectilinear space delineated by the channel arms 30 and webs 29 is filled with a spline 33 (see FIG. 5) of heat resistant or refractory material as will be explained below.

The arms 30 of the channels 27 or 28 also are utilized as mounting means for the panels on a building. In building construction the tolerance for the positioning of buildplus or minus one-quarter inch and often times dimensions vary to an even greater degree. It is necessary therefore that the means by which the prefabricated panels 24 or 26 are mounted on the building shall accommodate this much variation.

A typical mounting means is shown in place in FIG. 1 and illustrated in detail in FIGS. 2 and 3. Slotted blocks surfaces of the floors 21 and 22, being spaced horizontally on centers substantially equidistant to the horizontal dimension of the prefabricated building panels 24 and 26. Each of the blocks 34 has a longitudinally extending T-slot 35 in which are engaged the heads of two bolts 36. Each of the bolts 36 extends upwardly through a transverse slot 37 in one arm of a short angle bracket 38. The other arm 3 of the angle bracket 38 has a pair of transversely extending slots 39 through-which panel mounting bolts 40 (FIG. 2) can be inserted. The bolts 40 are engageable with nuts 41 (see FIG. 5) that are welded or otherwise secured on the inner sides of the arms 30 of the channels 27 or 28.

The T-slots of the blocks 34 provide for horizontal adjustment in one direction, the slots 37 in the angle bracket 38 provided for adjustment in the second horizontal direaction and the slots 39 in the bracket 38 provide for adjustment in the vertical direction. Thus panel mounting bolts 40 may be inserted into the fixed position nuts 41 of the prefabricated panels regardless of the variation in the dimensions of the building within the calculated tolerances. The mounting system just described for building panels according to the invention is merely illustrative of such systems and is not a part of the instant invention nor are the panels of the instant invention limited to being mounted in the fashion just described.

The vertical channels 27 and horizontal channels 28 function not only as frame members for the prefabricated panels according to the invention and as means by which those panels may be mounted upon the main building structure, but they also serve as structure for the assembly of the component elements of prefabricated panels according to the invention. In describing the component elements of prefabricated building panels according to the invention, each of the successive layers will be given a letter designation and each discussed in the corresponding one of the following paragraphs.

Component A.-In the embodiment of the invention illustrated in FIGS. 1, 4, and 5, Component A of the panel is an exterior facing layer and is shown as being a layer of blocks of split marble, arranged in courses with suitable mortar, caulking or grout between the adjacent vertical and horizontal edges of individual blocks of the split marble. Building panels according to the invention also may be fabricated using other exterior facing materials of various types such as, for examples, ceramic tile either in large pieces or in smaller pieces, often called ceramic mosaics, slate, thin brick veneering, metal plates coated with porcelain enamel, metal sheeting, aggregate of small rocks or pebbles embedded in a suitable matrix such as a weather resistant resinous material, and the like. It is to be understood that the selection of the particular exterior facing is determined by the building architect and its fire resistance, acoustical insulation and structural strength are additive to those which will be discussed with respect to the combination of other components of a building panel embodying the invention. It is also to be understood that, regardless of what particular material is selected for the exterior facing, the pieces thereof, either in sections or slabs, are adhered to the exterior surface of the next interior layer of a prefabricated panel at the time of the original fabrication of the panel in the panel factory. Suitable exterior caulking, shown in FIG. 5, is later inserted between the adjacent edges of the surface layers of prefabricated panels by the installation workmen at the time of erection of the prefabricated panel onto the building structure.

Component B.-Component B of the panel illustrated in the drawings is a layer of bonded asbestos board (BAB) in this instance oneeighth inch thick, to the outer face of which the exterior facing layer, Component A, is adhered by a thin layer of adhesive, for example a commercially available epoxy. The BAB component is a principal structural element of a prefabricated building panel according to the invention. The BAB layer is adhered not only to the exterior facing layer, Component A, but also to the next interior layer, Component C.

Component C.-In the illustrated embodiment of the invention, Component C is a one-half inch thick layer of fire resistant gypsum board. Component C is adhered to the interior surface of the BAB layer, Component B, and also to the outer sides of the arms 30 of the channels 27 and 28 as well as similar flanges on the studding channels 32, if used. The vertical edges of the fire resistant gypsum board, Component C, are aligned with the vertical edges of the arms 30 of the vertical channels 27 and all of the edges around the perimeter of the gypsum board, Component C, are coated with a sealant, such as a waterproof or moisture resistant resinous material to seal the edges of the board.

In addition to the adhesion of the Component C layer to the arms 30 of the vertical channels 27, additional mechanical strength is provided in the prefabricated panels by use of fastening means, such as a plurality of blind rivets 42 or the like, the heads of which are recessed in the outer surface of the BAB layer, Component B, and which extend through predrilled holes in the arms 30 of the channels 27. A sufficient number of rivets 42 is employed along each of the vertical channels 27 and/or horizontal channels 28 so as to structurally attach the BAB, Component B, and the gypsum layer, Component C, to the frame forming channels. If desired, additional strength may be obtained in the panel structure by similarly mechanically securing the Component B and C layers to the flanges of the studding channels 32.

Component D.-In the illustrated embodiment of the invention, Component D is a layer of a special densified glass fiber board which is adhered to the inner surface of the gypsum layer, Component C. The densified glass fiber board forming Component D which is suitable for use in a panel according to the invention is selected from those types of densified glass fiber wool (i.e., boards) which have particularly effective resistance to elevated temperatures. Glass fiber boards are usually fabricated from glass fibers which are produced by one of several known processes, such as the steam blown process, the flame blowing process, or the rotary process. In these processes, glass is supplied to the steam blower, the flame blower or to a rotary centrifuge from which it is projected in the form of streams into an attenuating blast having high kinetic energy. In all of these processes, the glass is attenuated or blown out into fine fibers of varying lengths by the force of a steam jet, or of a high velocity burner, such as a combustion products burner. In any event, depending upon the fineness of the diameter of the fibers which it is desired to produce, the blown or attenuated fibers are collected upon an accumulating belt in a fluffy, loose blanket, having been sprayed or otherwise admixed with a suitable binding material, usually a resin. The fibers are not interwoven but are randomly intermingled with each other, some of them lying generally parallel to the surfaces of the fluffy mass and some lying substantially normal thereto.

In either case, the coating material or binder may be applied in sufiicient quantity merely to bond the fibers to each other at their points of intersection or it may be supplied in larger quantities to at least partially fill the voids between the fibers in their inter-matted relationship. The loose, fluffy mass of fibers is then densified, usually by being passed between compression rollers to reduce its depth to a desired thickness and increase its apparent density (weight per cubic foot) to the desired degree. For example, a six or eight inch blanket of loosely felted fibers may be reduced in thickness to one inch and the finished thinner board, of course, has an apparent density in pounds per cubic foot six or eight times as great as that of the original loose, fiulfy mass. The final apparent density depends, not only upon the degree of compression relative to its original loose condition, but also upon the original thickness of the mass, which results from the rate of deposition of the fibers relative to the lineal movement of the collecting conveyor.

After compression to the desired thickness and apparent density, the resinous binder is set up to bond the fibers to each other to produce a stiff board-like mass of glass fibers bonded together by the resinous material in the desired thickness and apparent density in pounds per cubic foot.

Various synthetic resinous materials may be used in these binders, for example, phenolic resoles which, when cured or otherwise converted to a hard condition, are dimensionally stable and resist variations in humidity. Because the glass fibers themselves similarly resist such variations, the finished boards are dimensionally stable and suitable for use in locations such as the prefabricated building panels embodying the invention where possible changes in the humidity in the interior of the panels may be expected.

However, most previously known fibrous board-like materials produced in the fashion outlinedare comparatively lacking in resistance to elevated temperatures. If such a board is placed in a furnace having a temperature in the order of, say, 1,500" F., the binder composition breaks down and after a relatively short time the fibers themselves fuse together and form a blackened glob which has approximately the general configuration of the original piece, but has shrunk substantially in lineal dimension.

The special glass fiber boards which have particular utility in a prefabricated building panel according to the invention are upgraded substantially relative to temperature resistance in several difierent manners. Some such boards are improved by the addition of finely divided fibrous talc in the binder composition; some by the addition of both fibrous talc and titania in the binder composition and some still further improved by post-impregnating the interstices of the boards with a suitable clay. In this type of glass fiber board, the fibrous talc apparently causes the glass fibers in the board to devitrify as the board is heated to elevated temperatures, e.g., higher than about 1,000 F. As a consequence, the fibers are much more resistant to the elevated temperature. When the board contains both fibrous talc and titania in the binder constituents, the board not only is more resistant to higher temperatures but it also is stiffer at these elevated temperatures. In addition, when the fiber board is impregnated with clay and subjected to temperatures in excess of about 1,000 F., the clay supplements the fibrous talc or fibrous talc and titania by becoming an effective binder for the glass fibers and replacing the phenolic or other synthetic resinous binder which is consumed or rendered relatively ineffective at such high temperature.

In the particular special glass fiber boards used in making up Component D of a test panel illustrated in FIGS. 6-7, and thus suitable for use in building panels according to the invention, the apparent density of the glass fiber mass was ten pounds per cubic foot and it was formed with ten percent by weight resin solids as a binder with a ratio of about 4:5 between the resin solids in the binder to parts by weight of fibrous talc and titania. The fibrous talc was about ninety percent of the combination. In other prefabricated building panels embodying the invention where additional acoustical insulation and a higher fire resistance might be desired, the glass fiber board of this type. may be impregnated with a suitable clay, for example an aluminum silicate clay containing, say, 40 to 50 parts by weight of silica chemically combined with 35 to 40 parts by weight of alumina and' with other miscellaneous ingredients, and generally called Georgia kaolin. Such impregnation increases the resistance of the special glass fiber board to elevated temperature and increases its resistance to the transmission of sound energy.

The layer of special glass fiber board which forms Component D of the assembly, extends between the outer surface of the crosswebs 29 of the channels 27 and 28, and studding channels 32.

Component E.Component E is a continuous sheet of thin metal, such as aluminum foil, that is adhered on the one side to the special glass fiber board, Component and on the other side to an intermediate gypsum board layer, Component F. The aluminum foil, Component E, functions as a moisture barrier and a thermal reflector and contributes to the acoustical properties of the panel because it is acoustically opaque and is firmly adhered in place by the two layers of adhesive to the massive intermediate gypsum board layer, Component F, and the densified glass fiber board, Component D. The sheets of aluminum foil forming Component E are continuous between the channels 27 and studding channels 32.

In the fire test panels illustrated in FIGS. 67 inclusive, the aluminum foil sheet, Component E, was in the position indicated in FIG. 5. Similar layers also can be advantageously inserted in other locations in the panel at a position closer to the interior of the building, so as to more quickly oppose the passage of moisture vapor, for examples on the outer side of the innermost layer, Component H, or on the inner side of an interior layer of glass fiber board, Component G, as described below.

Component F.Component F is a second layer of fire resistant gypsum board, similar to Component C, and, like the other components of the panel, is continuously adhered over its surface to the adjacent aluminum foil, Component E, and to a next interior layer of special glass fiber board, Component G.

Component G.Component G is a second layer of special densified glass fiber board identical with that forming Component D and, like the other components of the invention, is continuously adhered by a layer of adhesive to the adjacent gypsum board layer, Component F, and, at its edges, to the channels 27 and 28 and the studding channels 32.

'The crosswebs 259 of the channels 27 and 28 and the studding channels 32 are wider than the total thickness of the three layers Components D, F and G. When the final interior layer of the panel (Component H) is added, there is a dead air space in the order of three-quarters inch to one inch thick, as indicated by the legend Air in FIG. 5, defined by the inner side of the layer of glass fiber board, Component G, the crosswebs 29 of the channels 27 and 28 and the studding channels 32, and the outer side of the interior finish layer, Component H.

Component H.This component, labeled as an interior layer and bearing the additional word added constitutes a part of a finished building panel embodying the invention but is added by the building workmen after the installation of the prefabricated assembly of Components A-G, inclusive. The interior finish layer, Component H, may be a typical drywall construction, being shown as a sheet of gypsum board, or may be another fire rated material comparable thereto. In the tested panel shown in FIGS. 6 and 7, gypsum board was used.

In order to minimize the transmission of sound and the penetration of moisture through a prefabricated panel embodying the invention and to contribute to its fire resistant properties, the joints in the layers of material making up the several Components A-H inclusive, are staggered relative to each other as can best be seen in FIG. 4 where the horizontal lines leading from the legends Joint indicate the horizontal joints, for example, between vertically juxtaposed sheets of BAB in Component B and between the edges of vertically juxtaposed sheets of glass fiber board in Components D and G and gypsum board in Components C, F and H. It will also be observed that the sheets of aluminum foil, Component E, are continuous between the channels 27 and 28 and the studding channels 32 and are adhered over their entire surfaces.

In the building panel so far described which embodies the invention, it has been indicated that the decorative exterior facing material, Component A, would be adhered to the surface of the panel only by the layer of adhesive between its inner face and the outer face of the layer of BAB, Component B. If desired and if required by a particular building code, of course, mechanical mounting means for the exterior facing layer may be provided on the vertical channels 27, the horizontal channels 28 or the studding channels 32, or two or three of these structural members.

The prefabricated building panel itself comprises two side channels 27, the top and bottom horizontal channels 28 and a suitable number of studding channels 32 and may, for convenience, be built in modular sizes, say, four feet wide by eight feet tall, five feet wide by ten feet tall, and similar sizes thus simplifying fabrication, shipment, handling and erection.

As earlier mentioned, where the vertical edges of two prefabricated panels according to the invention are adjacent each other, the outwardly turned arms 30 of the side channels 27 define a vertically elongated hollow space. This space is filled with the spline 33 at the time of erection of the prefabricated panels on the building. After each unit of a prefabricated panel according to the invention is erected on the building, a spline 33 is inserted into the side channel 27 of that panel and then the next adjacent panel assembled in place so that the arms of its vertical channel 27 embrace the spline 33. While the particular material from which the spline 33 is fabricated is not critical in a building panel according to the invention, a suitable material has been found to be a lime/silica composition reinforced by a high percentage of asbestos fibers. In any event, the spline 33 should be fabricated from a refractory material and the outer surfaces of the spline 33 should be coated with some form of adhesive by which it is bonded to the interior surfaces of the vertical channels 27. It will also be observed in FIG. that the transverse thickness of the spline 33 is greater than the sum of the lengths of the arms 30 of the two mating vertical channels 27 thus leaving a space between the vertical margins of the arms 30 and between the edges of the two outermost layers, Components B and C. This space is closed, on at least the exterior side of the preassembled panel, by an epoxy resin filled with finely ground silica sand weighing from 100 to 150 percent of the weight of the epoxy resin itself, indicated in FIG. 5 by the legend Silica filled resinous material."

The fire test building panel embodying the invention and illustrated in FIGS. 6-7, inclusive, measured ten feet by ten feet in overall dimension and comprised two adjacent sections 43 and 44, each of which was five feet wide and ten feet tall. The general structure of the panel tested was according to the invention as discussed above. Each section 43 or 44 comprised the following components:

(The fire test panel did not have an exterior facing layer, Component A.)

Component BOne-eighth inch cement asbestos board (Johns-Manville Corporation) Component COne-half inch fire resistant gypsum wall board (Bestwall Type X, Bestwall Gypsum Company, Ardmore, Pa.)

Component D-Thirteen-sixteenths inch thick, 6 lbs. per cubic foot apparent density, special glass fiber board (Owens-Corning Fiberglas Corporation) Component EAluminum foil, .00035 inch thick, 99.25% pure, dead soft (Alcoa Aluminum Company) Component FSarne as Component C Component GSame as Component D Component H-Five-eighths inch fire resistant gypsum wall board (Bestwall Type X, Bestwall Gypsum Company, Ardmore, Pa.)

The two sheets forming Components B and C were secured by explosive rivets 45 (FIG. 7) to the front arms of vertical side channels 46, horizontal channels 47, defining the top and bottom of the prefabricated panels, and studding channels 48. The gypsum board layer, Component H, was also mechanically secured to the back arms of the several channels 46, 47, and 48 by sheet metal screws 49 spaced approximately twelve inches on centers. In addition, all surfaces of all component layers B-G inclusive, were laminated to each other with percent by weight, silica filled epoxy resin, the particular epoxy resin being designated A25-B35 by Alloyment Company. Any commercially available epoxy resin thus loaded with silica would be suitable for panels embodying the invention.

The vertically extending center joint between the two panel sections 43 and 44, which measured approximately one-quarter inch in width, was filled with a compound consisting of an epoxy resin filled with 150 percent by weight of mesh silica sand. Again, the epoxy resin was a standard type epoxy such as that mentioned above. A refractory spline (such as the spline 33 of FIGS. 4 and 5) was embedded between the mating arms of the two centrally positioned vertical channels 46. In the fire test panel, the spline was a cast piece of asbestos fiber filled diatomaceous silica bonded with an inorganic binder, the particular material having been obtained under the trademark Marinite from Johns-Manville Corporation.

In all aspects the test panel illustrated in FIGS. 6 and 7 was identical in construction with the panel embodying the invention as already described and illustrated in FIGS. l-S, inclusive, except for the presence on the panel of FIGS. 15 of the exterior facing layer, Component A. Therefore, the fire tests and the results thereof are valid for panels embodying the invention and indeed, by the addition of the facing or decorative panel, Component A, the properties of a finished erected panel embodying the invention are even better than those of the test panel in the test now to be described.

The test panel assembly comprising the two sections 43 and 44 was erected in a test stand having an opening ten feet by ten feet in size, each of the two panel sections measuring approximately five feet by ten feet, the opening being defined by a heavy concrete frame 50 and supported by structural beams 51 forming the sides and 52 forming the top and bottom. The test stand was located in the Building Research Laboratory of Ohio State University, Columbus, Ohio. In this test, live flames played directly upon the exposed surface of the interior gypsum layer, Component H.

Ten pairs of thermocouples were attached to the opposed surfaces of the two panel sections 43 and 44, the thermocouples on opposite sides being positioned in alignment with each other, the low temperature side being illustrated in FIG. 6. The thermocouples on the exposed and unexposed surfaces of the panels were located at the positions indicated by the thermocouples Nos. 11-20, inclusive, of FIG. 6 with thermocouples Nos. 1-10, inclusive, being positioned on the exposed side of the panel opposite their correspondingly numbered thermocouples thusly:

Thermocouple Alignment Exposed Unexposed Exposed Unexposed All twenty of the thermocouples were connected to a recording instrument and the tabulation set forth below shows the temperatures recorded by each of the thermocouples during a fire test identified by Ohio State University Building Research Laboratory as Test No. T-2839. The test data curve of FIG. 8 is a summary of the information set forth on the tabulation below in which the solid curve Average Furnace Temperature (Thermocouples 1-10 incl.) connects the arithmetical averages of the readings of the ten thermocouples on the exposed side of the test panels at the times indicated. The curve indicated by the legend Highest Temperature Thermocouple No. and the numbers appearing just above this curve, viz, 18, 18, 18, 16, 14, and 18, indicate the highest temperature reached on the unexposed side of the test panel at the elapse of 20, 40, 60, 80, 100 and 120 minutes, respectively. The dotted line curve bearing the legend Aver. Temp. (Thermocouples 11-20 incl.) connects the arithmetical averages of the temperatures of the ten thermocouples on the unexposed side of the test panel at the elapsed times indicated. FIG. 8 shows a temperature of 394 F. and a time of 124 minutes at the end of the curves.- This is the allowable high temperature under the test conditions but is not set forth on the tabulation below because it was visually observed by the test monitors rather than recorded by the automatic recording devices.

channels to secure the same in assembled relationship, and a densified, high temperature resistant, glass fiber board of a thickness less than such cavity adhesively adhered to the inner surface of said first layer of gypsum Wall board, said glass .fiber board having a rectangular periphery adhesively secured to the adjacent inner surfaces of said rectangular perimeter frame.

2. The prefabricated building panel of claim 1 which further includes an interior layer of gypsum board adhered to said glass fiber board in such cavity and a second similar glass fiber board in such cavity adhered to the opposite side of said interior layer of gypsum board.

3. The prefabricated building panel of claim 1 which further includes an impervious continuous sheet of aluminum foil extending across such cavity and adhered to one of said interior layers of said panel.

Time in Min.

Thermocouple Temperature in Degrees F.

The utilization of a high silica content epoxy resin for adhesion of the several elements of the building panel to each other and the still higher silica content epoxy as a grouting between the edges of sections of the panel further contributes to its fire resistance because at elevated temperature even though the epoxy resin itself may break down at such temperatures, the silica in the epoxy resin fuses, retaining the panel elements in assembled relationship and continuing to seal the interstices or cracks be tween adjacent pieces of the facing materials.

What we claim is:

1. A prefabricated fire resistant building panel consisting of spaced vertical channels and top and bottom horizontal channels forming a rigidrectangular perimeter frame with each of said channels liaving a generally U- shaped cross section with the arms thereof extending outwardly, sheets of gypsum wall board extending entirely across said frame in contact with the outer sides of said arms of said channels on both the front and back of said frame to form, with said frame, an enclosed continuous cavity between said gypsum sheets, a cement asbestos board co-extensive with and adhered to the outer surface of the first of said sheets of gypsum board, mechanical fasteners extending through said cement asbestos board, the first of said sheets of gypsum wall board and the adjacent arms on said frame channels to secure the same in assembled relationship, mechanical fasteners extending through the other of said sheets of gypsum wall board and the adjacent arms on said frame 4. A wall comprising a pair of prefabricated building panels according to claim 1 assembled in vertical edge-toedge adjacency with their respective channel members defining a vertically extending rectilinear space therebetween and with the vertical edges of the surface layers of said panels closely spaced, a refractory spline substantially filling such rectilinear space between the flanges of said channel members, and high temperature resistant, silica loaded, resinous filling material grouting the space between the edges of said surface layers.

FRANK L. ABBOTT, Primary Examiner. I. L. RIDGILL, Assistant Examiner. 

1. A PREFABRICATED FIRE RESISTANT BUILDING PANEL CONSISTING OF SPACED VERTICAL CHANNELS AND TOP AND BOTTOM HORIZONTAL CHANNELS FORMING A RIGID RECTANGULAR PERIMETER FRAME WITH EACH OF SAID CHANNELS HAVING A GENERALLY USHAPED CROSS SECTION WITH THE ARMS THEREOF EXTENDING OUTWARDLY, SHEETS OF GYPSUM WALL BOARD EXTENDING ENTIRELY ACROSS SAID FRAME IN CONTACT WITH THE OUTER SIDES OF SAID ARMS OF SAID CHANNELS ON BOTH THE FRONT AND BACK OF SAID FRAME TO FORM, WITH SAID FRAME, AN ENCLOSED CONTINUOUS CAVITY BETWEEN SAID GYPSUM SHEETS, A CEMENT ASBESTOS BOARD CO-EXTENSIVE WITH AND ADHERED TO THE OUTER SURFACE OF THE FIRST OF SAID SHEETS OF GYPSUM BOARD, MECHANICAL FASTENERS EXTENDING THROUGH SAID CEMENT ASBESTOS BOARD, THE FIRST OF SAID SHEETS OF GYPSUM WALL BOARD AND THE ADJACENT ARMS ON SAID FRAME CHANNELS TO SECURE THE SAME IN ASSEMBLED RELATIONSHIP, MECHANICAL FASTENERS EXTENDING THROUGH THE OTHER OF SAID SHEETS OF GYPSUM WALL BOARD AND THE ADJACENT ARMS ON SAID FRAME CHANNELS TO SECURE THE SAME IN ASSEMBLED RELATIONSHIP, AND A DENSIFIED, HIGH TEMPERATURE RESISTANT, GLASS FIBER BOARD OF A THICKNESS LESS THAN SUCH CAVITY ADHESIVELY ADHERED TO THE INNER SURFACE OF SAID FIRST LAYER OF GYPSUM WALL BOARD, SAID GLASS FIBER BOARD HAVING A RECTANGULAR PERIPHERY ADHESIVELY SECURED TO THE ADJACENT INER-SURFACES OF SAID RECTANGULAR PERIMETER FRAME. 